And if a man has these gene variants and a family history of prostate cancer his risk of developing the disease increases more than percent. For a man with five gene variants and a family history the risk is increased tenfold. When family history of prostate cancer is added to the mix the results become more striking xu said. But if you have four of these variants your risk is increased fourfold which is something we have never seen before he said. In thenew england journal of medicine. Researchers found that among men with four of the five variants the risk of prostate cancer is increased percent to percent compared to men with none of the variants.